US7741950B2 - Humidity sensor and a method for manufacturing the same - Google Patents

Humidity sensor and a method for manufacturing the same Download PDF

Info

Publication number
US7741950B2
US7741950B2 US11/577,338 US57733805A US7741950B2 US 7741950 B2 US7741950 B2 US 7741950B2 US 57733805 A US57733805 A US 57733805A US 7741950 B2 US7741950 B2 US 7741950B2
Authority
US
United States
Prior art keywords
moulding
encapsulation
dead
membrane
humidity sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active, expires
Application number
US11/577,338
Other languages
English (en)
Other versions
US20080048822A1 (en
Inventor
Kristian Ehrhorn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sensirion AG
Original Assignee
Senmatic AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Senmatic AS filed Critical Senmatic AS
Assigned to SENMATIC A/S reassignment SENMATIC A/S ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: EHRHORN, KRISTIAN
Publication of US20080048822A1 publication Critical patent/US20080048822A1/en
Application granted granted Critical
Publication of US7741950B2 publication Critical patent/US7741950B2/en
Assigned to SENSIRION AG reassignment SENSIRION AG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SENMATIC A/S
Active legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/121—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid for determining moisture content, e.g. humidity, of the fluid

Definitions

  • the present invention relates to a humidity sensor as well as to a method for manufacturing said humidity sensor.
  • Humidity sensors of this type are nevertheless unsuited for use under conditions with condensation and moisture.
  • the reason for this is, that the dead-space volume may be several thousand mm 3 , allowing the amount of water condensing inside the encapsulation dead-space volume to accumulate and get so large, that it becomes a significant problem because of the irreversible damage it may cause on the sensing element.
  • An object of the present invention is to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide a humidity sensor which may be used in wet and condensing environments.
  • a practical shape for the dead-space volume like a truncated cone or a trumpet like duct may be advantageously, where a porous membrane covers the big end of that cone or duct and the sensor element is placed in the opposite smaller end.
  • the cylindrical surface of the cone or trumpet tube is mainly made and formed of the moulding material and the hole in the external encapsulation may also be a part of this cylindrical surface.
  • the height of the dead-space volume is made as small as possible reducing the volume accordingly.
  • the area of the Teflon membrane is characterized by being large within practical limits, in order to maximize the effective area that water vapour is diffusing or breathing through.
  • the humidity sensor is characterized by the combination of a small dead-space volume and a large membrane area, which improves the humidity sensors ability to respond quickly to changes of humidity concentration in the ambient air and by a small dead-space volume that only contains a little amount of water vapour that may condense within it.
  • the sensor element When there is condensed water in the dead space volume, the sensor element is saturated with water and detects 100% relative humidity, but when the relative humidity of the ambient air is less than 100%, the ambient is able quickly to absorb and remove water from the dead-space volume allowing the sensor element to recover from a saturated condition back to normal sensitivity.
  • a ratio between an area of the membrane in relation to the dead-space volume may be larger than 1/5 (mm ⁇ 1 ), preferably larger than 1/3 (mm ⁇ 1 ), more preferably 1/2 (mm ⁇ 1 ), most preferably larger than 1/1 (mm ⁇ 1 ).
  • the invention relates to a humidity sensor, which is made robust in order to withstand water and condensing environment. It is characterized by embedding of a humidity sensor element into a moulding made of a thermoplastic material or a two component polyurethane epoxy or silicone casting which adheres to the internal surface of a metal or plastic encapsulation, housing or casing, shaped like a capsule or tube in which it is contained.
  • the sensor element which is sensitive to the relative humidity of air, is indirectly exposed to the ambient atmosphere by diffusion of air through the porous membrane, which has the function to protect the sensor element by isolating it selectively from the ambient atmosphere.
  • the membrane which preferably is made of porous Teflon (PTFE), is permeable to air and gases like water vapour, but effectively blocks transfer of liquid water and dust particles including substances like oil drops, bacteria, etc.
  • PTFE porous Teflon
  • the humidity sensor according to the invention has a construction where the size of the volume between the membrane and the sensor element, is designed to be small in order to minimize the amount of water molecules that may condensate to liquid water and wet the sensor element in this volume.
  • This volume between the membrane and the sensor element will further in this document be referred to as the dead-space volume.
  • the dead-space volume is less than 100 mm 3 , preferably less than 50 mm 3 , more preferably less than 25 mm 3 and most preferably between 1-15 mm 3 .
  • the active membrane area may be greater than 10 mm 2 .
  • the moulding material used in the invention may be a two-component polyurethane, epoxy or silicone material, which adheres to the internal surface of the external encapsulation.
  • the moulding material may also be a thermo plastic material with low viscosity, which is suitable for low-pressure injection moulding of electronic components.
  • the advantage of the injection moulding is the short curing time of less than a minute.
  • the invention also relates to a method for manufacturing the humidity sensor by a moulding process which in combination with a heating process is making the plastic moulding material adhere effectively to the inside of the metal encapsulation.
  • the moulding is made in two or more successive process steps, where the first step is a moulding of the PCB (Printed Circuit Board) with the sensor element and the associated signal processing electronics.
  • the metal bushing(s) for the mounting hole(s) are also integrated, and a core in the mould shapes the orifice and the dead-space volume containing the sensor element.
  • the first moulding is placed inside a thin external metal encapsulation, which fits to the shape of the first moulding, and where an orifice gives access to the dead-space volume over sensor element.
  • the metal encapsulation also has mounting holes that aligns with the holes in the bushings in the first cast and a hole in the side for the cable.
  • the metal encapsulation is heated from the outside to a temperature that is high enough to melt the surface of the moulding material inside the encapsulation. This makes the moulding adhere to the inside surface of the encapsulation and make a tight lamination because the moulding material has the properties of a hot melting glue.
  • a further injection moulding may be necessary to make a nice plane filling of the bottom of the encapsulation, as the shrinking properties of the plastic material makes it impractical to make the mould in only one step.
  • FIG. 1 shows a humidity sensor with an encapsulation 4 , a hole 11 with a bushing 10 for mounting the device and finally a PCB 6 , on which the electronic components and the humidity sensor are mounted.
  • FIG. 2 shows details of FIG. 1 , where the porous membrane 1 is glued on to the external encapsulation 4 and where the PCB 6 with the sensor element 5 are cast into a moulding compound 3 , which is adhering to the inside of the external metal or plastic encapsulation 4 .
  • FIG. 3 shows the same as FIG. 2 except for the membrane 1 , which is placed between the encapsulation 4 or the moulding 3 .
  • FIG. 4 shows the same as FIG. 2 except that the external encapsulation 4 is absent and the membrane 1 is glued directly on to the moulding compound 3 , which together with the membrane 1 , form the external surface of the humidity sensor.
  • the humidity sensor according to invention reduces the water exposure to the sensor element 5 , from condensing water vapour. This is achieved by making the dead-space volume 2 between the membrane 1 and the sensor element 5 as small as a few mm 3 which is a reduction of about typically 3 orders of magnitudes, compared to the dead-space volume of known humidity sensors. This construction leaves very little water in the dead-space volume 2 for possible condensing, and if condensing has taken place it allows the dead-space volume to evaporate the excess liquid water quickly out to the ambient through the relatively big membrane 1 .
  • the membrane 1 may be placed between the external encapsulation 4 and the moulding 3 and glued to one or both of these.
  • the invention also provides a construction method of a humidity sensor which effectively encapsulates the sensor element 5 by a multi step moulding of the PCB 6 and the sensor element 5 in a thermo plastic compound 3 .
  • the first step of the moulding process is the moulding of the PCB 6 , which is holding the sensor element 5 and one or more bushings 11 .
  • This primary moulding is then placed inside a protective encapsulation 4 where it fits precisely. For a few seconds the encapsulation is heated from the outside and this transfers just enough heat through the metal to melt the surface of the internal moulding 3 and make it glue efficiently to the inside of the hot external encapsulation 4 which is cooled down from the outside to allow the moulding 3 to cure again.
  • the plastic moulding material has properties similar to hot melting glue.
  • a last optionally moulding has the purpose of filling the external encapsulation 4 completely with moulding 3 .
  • the humidity sensor can be fastened on a smooth surface or wall, by a screw through the mounting hole 11 , which is reinforced by the bushing 10 , which hinders the force from the screw to deform the sensor and damage the internal PCB 6 .

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
US11/577,338 2004-10-18 2005-10-17 Humidity sensor and a method for manufacturing the same Active 2027-07-03 US7741950B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DK200401590 2004-10-18
DKPA200401590 2004-10-18
PCT/DK2005/000667 WO2006042546A1 (en) 2004-10-18 2005-10-17 A humidity sensor and a method for manufacturing the same

Publications (2)

Publication Number Publication Date
US20080048822A1 US20080048822A1 (en) 2008-02-28
US7741950B2 true US7741950B2 (en) 2010-06-22

Family

ID=35462151

Family Applications (1)

Application Number Title Priority Date Filing Date
US11/577,338 Active 2027-07-03 US7741950B2 (en) 2004-10-18 2005-10-17 Humidity sensor and a method for manufacturing the same

Country Status (5)

Country Link
US (1) US7741950B2 (de)
EP (1) EP1810013B1 (de)
CN (1) CN101040181B (de)
DK (1) DK1810013T3 (de)
WO (1) WO2006042546A1 (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100212433A1 (en) * 2009-02-25 2010-08-26 Werner Hunziker Sensor in a moulded package and a method for manufacturing the same
US20180011076A1 (en) * 2016-07-11 2018-01-11 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture
US11047753B2 (en) 2018-12-27 2021-06-29 Therm-O-Disc, Incorporated Pressure sensor assembly and method for manufacturing a pressure sensor assembly
US20220276114A1 (en) * 2019-08-06 2022-09-01 Orbital Systems Ab Leakage detector system
DE202023102702U1 (de) 2023-05-17 2023-06-05 Sensirion Ag Schutzvorrichtung für Sensoren, insbesondere Feuchtesensoren
US11815504B2 (en) 2016-07-11 2023-11-14 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2273261B1 (de) * 2009-07-09 2013-06-19 Sensirion AG Sensorvorrichtung auf einem flexiblen Träger
US20140076026A1 (en) * 2012-09-20 2014-03-20 Therm-O-Disc, Incorporated Relative humidity sensor
EP2871152B1 (de) 2013-11-06 2017-05-24 Sensirion AG Sensorvorrichtung
GB2568633B (en) 2016-09-21 2022-06-29 Sensirion Ag Gas sensor
JP2019529923A (ja) * 2016-09-29 2019-10-17 アイディーティー・インコーポレイテッド 気体検知モジュール用疎水性かつ疎油性カバー
TWM569412U (zh) * 2018-08-07 2018-11-01 捷騰光電股份有限公司 溫濕度感測模組之烘乾裝置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4562725A (en) 1982-07-31 1986-01-07 Shimadzu Corporation Moisture sensor and a process for the production thereof
US4856320A (en) 1988-09-08 1989-08-15 Universite Du Quebec A Trois-Rivieres, Societe Quebecoise D'initiatives Petrolieres And Gaz Metropolitain Inc. Method and apparatus for measuring physical adsorption of gases based on dielectric measurements
US4900405A (en) * 1987-07-15 1990-02-13 Sri International Surface type microelectronic gas and vapor sensor
US5608374A (en) * 1992-02-14 1997-03-04 Seiko Epson Corporation Humidity sensor and a method of producing the humidity sensor
US5777206A (en) * 1995-06-30 1998-07-07 Zuechner; Klaus Method and measuring device for determining the water content of a gas
US20020173922A1 (en) 2001-04-04 2002-11-21 Potyrailo Radislav Alexandrovich Devices and methods for simultaneous measurement of transmission of vapors through a plurality of sheet materials
US6812821B2 (en) * 2001-05-31 2004-11-02 Ngk Spark Plug Co., Ltd. Humidity sensor
US6840103B2 (en) * 2000-07-19 2005-01-11 Lg Electronics Inc. Absolute humidity sensor

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2080670U (zh) * 1990-11-27 1991-07-10 北京工业大学 电容式有机膜湿度传感器
CN1024232C (zh) * 1991-08-27 1994-04-13 中国原子能科学研究院 湿敏电阻器及其制备方法
CN1099590C (zh) * 1994-12-29 2003-01-22 Nec东金株式会社 湿度传感器
CN1241720A (zh) * 1998-11-13 2000-01-19 康达（成都）电子有限公司 一种湿度传感器及其制造方法

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4562725A (en) 1982-07-31 1986-01-07 Shimadzu Corporation Moisture sensor and a process for the production thereof
US4900405A (en) * 1987-07-15 1990-02-13 Sri International Surface type microelectronic gas and vapor sensor
US4856320A (en) 1988-09-08 1989-08-15 Universite Du Quebec A Trois-Rivieres, Societe Quebecoise D'initiatives Petrolieres And Gaz Metropolitain Inc. Method and apparatus for measuring physical adsorption of gases based on dielectric measurements
US5608374A (en) * 1992-02-14 1997-03-04 Seiko Epson Corporation Humidity sensor and a method of producing the humidity sensor
US5777206A (en) * 1995-06-30 1998-07-07 Zuechner; Klaus Method and measuring device for determining the water content of a gas
US6840103B2 (en) * 2000-07-19 2005-01-11 Lg Electronics Inc. Absolute humidity sensor
US20020173922A1 (en) 2001-04-04 2002-11-21 Potyrailo Radislav Alexandrovich Devices and methods for simultaneous measurement of transmission of vapors through a plurality of sheet materials
US6812821B2 (en) * 2001-05-31 2004-11-02 Ngk Spark Plug Co., Ltd. Humidity sensor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100212433A1 (en) * 2009-02-25 2010-08-26 Werner Hunziker Sensor in a moulded package and a method for manufacturing the same
US8156815B2 (en) 2009-02-25 2012-04-17 Sensirion Ag Sensor in a moulded package and a method for manufacturing the same
US20180011076A1 (en) * 2016-07-11 2018-01-11 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture
US10126288B2 (en) * 2016-07-11 2018-11-13 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture
US11815504B2 (en) 2016-07-11 2023-11-14 Quipip, Llc Sensor device, and systems and methods for obtaining measurements of selected characteristics of a concrete mixture
US11047753B2 (en) 2018-12-27 2021-06-29 Therm-O-Disc, Incorporated Pressure sensor assembly and method for manufacturing a pressure sensor assembly
US20220276114A1 (en) * 2019-08-06 2022-09-01 Orbital Systems Ab Leakage detector system
DE202023102702U1 (de) 2023-05-17 2023-06-05 Sensirion Ag Schutzvorrichtung für Sensoren, insbesondere Feuchtesensoren

Also Published As

Publication number Publication date
CN101040181A (zh) 2007-09-19
EP1810013A1 (de) 2007-07-25
EP1810013B1 (de) 2012-06-13
US20080048822A1 (en) 2008-02-28
DK1810013T3 (da) 2012-08-13
CN101040181B (zh) 2010-09-29
WO2006042546A1 (en) 2006-04-27

Similar Documents

Publication Publication Date Title
US7741950B2 (en) Humidity sensor and a method for manufacturing the same
US8156815B2 (en) Sensor in a moulded package and a method for manufacturing the same
US10168241B2 (en) Drying module for a relative pressure measuring transducer
KR101957133B1 (ko) 유체의 유동 특성을 검출하기 위한 센서 장치
US20080016945A1 (en) Humidity detector for detecting fogging on a window
CN102834715A (zh) 应变式压力传感器
US20140076026A1 (en) Relative humidity sensor
JP2007163483A (ja) 複数の成分を含むガス状流体における所定の成分を検出する方法およびセンサ
US9598280B2 (en) Environmental sensor structure
JP6606608B2 (ja) 圧力センサ
JP3979911B2 (ja) 結露防止機能を備えたガスセンサ
CN108871662A (zh) 不存在内部捕获的流体的具有端口的压力传感器
US7617599B2 (en) Sensor packaging method for a human contact interface
US6186008B1 (en) Semiconductor sensor component
US7553071B2 (en) Sensor unit
JP2004279091A (ja) 圧力センサ
US20200386585A1 (en) Sensor package, method of manufacturing the same, and method of manufacturing lid structure
US7566965B2 (en) Semiconductor module
US6422085B1 (en) Flush-diaphragm relative pressure sensor
US9841391B2 (en) Hand-held test meter with integrated thermal channel
US20040081225A1 (en) Plastic enclosed sensor
TW200725822A (en) Package structure of micro gas sensor and making method thereof
US11162830B2 (en) Sensor device for detecting at least one flow property of a fluid medium
JP2002335090A (ja) 電子機器
US20130235262A1 (en) Method for packaging image sensor structure and image sensor structure formed from the same

Legal Events

Date Code Title Description
AS Assignment

Owner name: SENMATIC A/S, DENMARK

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:EHRHORN, KRISTIAN;REEL/FRAME:019166/0040

Effective date: 20070410

Owner name: SENMATIC A/S,DENMARK

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:EHRHORN, KRISTIAN;REEL/FRAME:019166/0040

Effective date: 20070410

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552)

Year of fee payment: 8

AS Assignment

Owner name: SENSIRION AG, SWITZERLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SENMATIC A/S;REEL/FRAME:055639/0516

Effective date: 20210309

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 12TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1553); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

Year of fee payment: 12